Browsing by Author "Laubscher, R."

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    Provincial differences in infant deaths in South Africa - An effect of antiretroviral interventions?
    (2011) Boulle, A.; Thompson, M. L.; Laubscher, R.; Johnson, L. F.; Sayed, R.; Brody, L. L.; Draper, B.; Cotton, M. F.; Abdullah, F.; Myers, J. E.; Bourne, D. E.
    Objective. It has previously been demonstrated that a peak in registered infant deaths, at 2-3 months of age at death, developed between 1997 and 2002 in South Africa, alongside the evolving HIV epidemic. The objective of this analysis was to explore the age distribution of post-neonatal infant deaths in South Africa by province, and relate the observed distributions to HIV and intervention characteristics. Design. Ecological study based on registered infant deaths and published HIV and intervention characteristics. Methods. Numbers of registered infant deaths beyond 1 month of age at death were plotted by year of death, province of South Africa and age at death in months, for the years 1997-2007. Results. The total number of registered deaths in infants aged 1-11 months increased from 15 404 in 1997 to 34 479 in 2006. Eight of the 9 provinces experienced an annual peak in registered infant deaths at 2-3 months of age between 1997 and 2007. This peak in mortality was not observed in the Western Cape. In 7 of 9 provinces registered post-neonatal infant deaths did not rise markedly in 2007 compared with 2005. Conclusions. We identified a single province out of 9 South African provinces in which a peak in early infant deaths at age 2-3 months did not occur during the period 1997-2007. This was the province with the earliest and highest coverage of antiretroviral interventions from 1999 onwards. It is possible that these interventions have averted the greater increase in early infant deaths seen in the rest of South Africa over this period.
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    Risk factors for the development of osteoporosis in a South African population. A prospective study
    (Health & Medical Publishing Group, 1994) Blaauw, Renee; Albertse, E. C.; Beneke, T.; Lombard, C. J.; Laubscher, R.; Hough, F. S.
    Despite the vast number of risk factors that apparently predispose to the development of osteoporosis (OP), they have not been accurately identified and given relative priority. In order to analyse possible risk factors prospectively in a local patient population with overt OP (histomorphometrically confirmed and characterised) and compare it with an appropriately matched non-OP control group (with normal bone mass on dual-energy X-ray absorptiometry), a detailed general history, risk factor analysis, dietary history and anthropometric data were obtained from 56 OP and 125 non-OP subjects. In females a positive family history of OP (P = 0,002), a fair complexion (P = 0,009), lower body mass (P = 0,02) and height (P = 0,03), no breast-feeding of babies (P = 0,006), a history of smoking (P = 0,001) and fat distribution around the waist (P = 0,009) were idenfified as risk factors. In males lack of exercise (P = 0,008), a history of smoking (P = 0,01), lower body mass (P = 0,04) and height (P = 0,04), a preference for salty food (P = 0,02) and fat distribution around the waist (P = 0,002) appeared to predispose. Dietary calcium, phosphorus, protein and caffeine intakes were similar in OP and control subjects, but alcohol consumption was clearly higher in both OP males (P = 0,001) and females (P = 0,01).
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    The effect of iron fortification on the fatty acid composition of plasma and erythrocyte membranes in primary school children with and without iron-deficiency
    (1994) Smuts, C. M.; Tichelaar, H. Y.; Van Jaarsveld, P. J.; Badenhorst, C. J.; Kruger, M.; Laubscher, R.; Mansvelt, E. P. G.; Benade, A. J. S.
    An intervention study was designed to evaluate the fatty acid (FA) status of children aged 6-11 years before and after iron fortification. Iron deficient (ID) and matched controls without ID (n = 30) were selected. All children received soup (160 mL) fortified with 20 mg iron and 100 mg vitamin C for 15 weeks on school days. Measurements before and after intervention included dietary intake, haematological and iron status and FA composition of plasma and erythrocyte membranes (EMBs). The prevalence of low plasma ferritin concentration and transferrin saturation decreased in the ID children by 40% and 56%, respectively, with intervention. Plasma FAs reflected dietary FA intake. In comparison with controls, the ID group presented with increased percentage total saturated FAs (SFAs; p = 0.0002) in their EMB phosphatidylcholine (PC) and reduced percentage total polyunsaturated FAs (PUFAs; p = 0.0037) before intervention. Lower total n-3 FAs (p = 0.0070) including eicosapentaenoic acid (EPA; p = 0.0034), docosapentaenoic acid (DPA; p = 0.0048) and docosahexaenoic acid (DHA; p = 0.0058) were observed in the ID group. The EMB phosphatidylethanolamine (PEA) of the ID children presented with lower percentages of α-linolenic acid (ALA; p = 0.0001), EPA (p = 0.0051) and DHA (p = 0.0084) compared to controls before intervention. Iron intervention was associated with an increase (p < 0.05) in the percentage of n-3 FAs in the EMB-PC and -PEA of the ID group to percentages comparable to that in the control group. It appears that iron status can influence FA metabolism of specific n-3 FAs in the EMBs of young children.
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    Unnatural deaths, alcohol bans and curfews : evidence from a quasi-natural experiment during COVID-19
    (Health & Medical Publishing Group, 2021-07) Moultrie, T. A.; Dorrington, R. E.; Laubscher, R.; Groenewald, P.; Parry, C. D. H.; Matzopoulos, R.; Bradshaw, D.
    Background: Coronavirus disease-19 (COVID-19) restrictions, particularly relating to the sale of alcohol and hours of curfew, have had a marked effect on the temporal pattern of unnatural deaths in South Africa. Methods: Death data were collected over 68 weeks from January 2020 to April 2021, together with information on the nature of restrictions (if any) on the sale of alcohol, and hours of curfew. Data were analysed using a simple ordinary least square (OLS) regression model to estimate the relative contribution of restrictions on the sale of alcohol and hours of curfew to the pattern of excess unnatural deaths. Results: The complete restriction on the sale of alcohol resulted in a statistically significant reduction in unnatural deaths regardless of the length of curfew. To the contrary, periods where no or limited restrictions on alcohol were in force had no significant effect, or resulted in significantly increased unnatural deaths. Conclusions: The present study highlights an association between alcohol availability and the number of unnatural deaths and demonstrates the extent to which those deaths might be averted by disrupting the alcohol supply. While this is not a long-term solution to addressing alcohol-related harm, it further raises the importance of implementing evidence-based alcohol control measures.
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    Utilization of basic multi-layer perceptron artificial neural networks to resolve turbulent fine structure chemical kinetics applied to a CFD model of a methane/air piloted jet flame
    (Yildiz Technical University, 2018) Laubscher, R.; Hoffmann, J. H.
    ENGLISH ABSTRACT: This work investigates and proposes an alternative chemistry integration approach to be used with the eddy dissipation concept (EDC) advanced combustion model. The approach uses basic multi-layer perceptron (MLP) artificial neural networks (ANNs) as a chemistry integrator for the reactions that take place in the fine structure regions created by the turbulence field. The ANNs are therefore utilised to predict the incremental species changes that occur in these fine structure regions as a function of the initial species composition, temperature and the residence time of the mixture in the fine structure regions. The chemistry integration approach for the EDC model was implemented to model a piloted methane/air turbulent jet diffusion flame (Sandia Flame D) at a Reynolds number of 22400. To prove the concept, a five-step methane combustion mechanism was used to model the chemical reactions of the experimental flame. The results of the new approach were benchmarked against experimental data and the simulation results using the standard integration approaches in Fluent. It was shown that once the ANNs are well-trained (in-sample error minimised as best possible), it can predict the species mass fractions with relative accuracy in a manner that is both time and computer-memory efficient compared with using traditional integration procedures.